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Tuesday, May 09, 2006

Risk, Disaster, and Mitigation 

As one of my minor hats at work, I'm a Floor Warden, which is a nice term for the people who wear colourful vests and order others out of the building in an emergency. This meant I got to attend an interesting presentation Monday on planning for emergencies and disasters (for the uninitiated, there's a difference: emergencies happen in the context of the rapid arrival of external professional help. In other words, the fire department will be there shortly. Disasters are that class of problem where services are overwhelmed (hurricanes, earthquakes, geography-spanning stuff like that) and there is an expectation you'll be on your own for a while.

The stuff stayed with me. I liked the succinct summary of disaster management: "nobody else dies."

Rather than talk about the very sensible guide to emergency and disaster procedures we got--and more particularly, the rationale behind those procedures--I was inspired to muse on what I might call "marginal risk management." That's a clever way of saying "put your effort into avoiding the most likely dangers." I suppose you could also make a case for cost-benefit analysis: it's worth dealing with relatively low-risk hazards that can be mitigated with little effort.

The real trick with marginal risk management is figuring out what the real dangers are. And although it was peripheral to the talk, our speaker mentioned the key one in passing: try not to die in a traffic accident.

Not all of the risk of car crashes can be avoided, except maybe by shut-ins. But you can do a few things when you get in a car that make your risk of death much less: seatbelts, don't be impaired or fatigued at the wheel (or, as in the fatal case of one of my high school classmates, take a ride from a drunk), don't drive like an idiot. Seatbelts and not being drunk are pretty boringly proven safety tricks, but most people already know that stuff and put it into practice.

Oh, brief aside: I'm not sure if it has real marginal value in saving lives, but electronic stability control (ESC) seems to be proving itself as a crash-and-fatality prevention device. ESC is basically a system where your car can sense certain patterns of acceleration and relative wheel motion (usually using accelerometers built into the car, and the ABS sensors on each wheel) that mean your car is sliding out of control, and then can either reduce engine power or apply the brakes (often one wheel at a time) to bring the car back into line. Surprisingly, anti-lock brakes themselves have shown no measurable benefit in reducing crashes or fatalities.

What's the next marginal danger? This page seems a good place to start, though note that figures on obesity as a cause of death are in flux.

The National Safety Council has a very interesting page on the odds of dying by a particular cause. That table is very interesting, because this seems to be about the rawest way of expressing causes of death one can get, but it is also very deceptive, in that it doesn't separate causes of death by "participation" level in these activities ("participate" is in scare-quotes because while one can assume that all people who died as "motorcycle riders" were participating in motorcycling, I am at a loss as to how to specify participation levels for "ignition or melting of nightwear" (though I'll bet that's primarily a smoker's death) or "contact with hot tap-water" (cold showers save lives? Or do they just increase deaths by "Excessive heat or cold of man-made origin"?)

What one really wants to know, odds-wise, are the odds for one's personal risk profile: Given that I drive X km/year in conditions Y, ride my bicycle Z km/year and always use blinky lights, and eat A pounds of sugar in my diet, have B history of diseases C, D, and E in my family, live in a house at risk due to natural disasters F and G, but not H, swim in the lake J times a year, and drink K glasses of alcohol every night, what are my chances of dying of a particular cause? Knowing that, what are the marginal changes I can make to my life, my activities, and the way I do them that will make the biggest difference for the least cost? How much risk does my lifestyle put me at? Even if The Big One hits Vancouver, is it very likely I'll die in it? What is the difference in the chance of survival if I am fully prepared, complete with food, water, and first aid for a week or so, or completely unprepared and reduced to drinking toilet tank water and draining the hot water heater (the two primary sources of potable water, by the way, if you have nothing else in the house)? What is my life worth? Four million dollars? One more drink before closing time? Worth giving up motorcycling?

Let me phrase it another way: is the car trip I make to the store to buy a first aid kit, water, and survival rations more likely to kill me than the emergency supplies are likely to save my life during a disaster? Note that even in a disaster, most people survive despite their level of emergency preparedness. The trick is you can improve your odds by preparation and planning for the during and after parts, so you don't end up surviving the earthquake, and then dying because you got hit by falling glass afterwards.

"Nobody else dies."

Maybe I'll have those emergency supplies delivered for me. I'm much less likely to fall and die in the house than to die in a car.

Risk calculation and disaster mitigation is complicated, but the questions brought up are not only creepy, they're interesting!

I'm seeing a career in the insurance industry in your future Ryan. Actuarial science, life tables, and Gompertz-Makeham law of mortality, here he comes!

Or perhaps software engineering.

Both deal heavily in risk, its mitigation, and its effects.
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